The present invention is directed to a transmitter and/or receiver unit with the extent of a handheld unit.
Current wireless transmitters with the said extent as e.g. 50-75 MHz wireless microphones, which operate in the VHF (160-230 MHz) and/or lower UHF (400-500 MHz) band, use the following types of antennas to transmit the low-power signal, normally only in the range of a few mW:
Wire antennas with a length of a quarter of the wavelength of the carrier signal;
helical antennas.
Both types of antennas are not very practical in handling, helical antennas have a fairly big volume and are therefore not very suited to be included or integrated in a tiny case as for handheld devices.
It is an object of the present invention to provide for a handsome transmitter and/or receiver device, which has the extent of a handheld device, operates in a frequency band B within 50 MHzxe2x89xa6Bxe2x89xa6500 MHz and transmits and/or receives with an electric power of at most 2 mW. Such a device is ideally suited to be used together with hearing devices, be it for transmitting signals to hearing devices of to receiving signals from hearing devices. Hearing devices may be e.g. consumer hearing devices, e.g. wireless headphones or hearing aid devices etc.
This is realized by the device comprising a transmitter and/or receiver antenna and a transmitter and/or receiver module, which is operationally connected to the antenna, a casing comprising two linked parts to be movable, at least a predominant part of said module being built into one of said parts, the other of said two parts comprising said antenna being a loop antenna.
Whereas loop antennas are well-known operating for high-power applications, such as radio navigation on ships or television and broadcasting transmitters and receivers, and further may also be found within modern mobile phone systems operating in the upper UHV band and lower microwave bands, such as GSM, DECT, PCS or UMTS, it must be considered that all these applications of loop antennas are not critical with respect to power consumption. For hearing device applications even including in-the-ear hearing aid applications there is considerably restricted space with respect to power supply. Therefore, the power of wirelessly transmitted signals is here at most 2 mW. Further, the addressed applications do not allow in view of the low-power consumption required to raise the frequency of the transmitted and/or received signals. Nevertheless and according to the present invention, it has astonishingly been found that the transmitter and/or receiver device mentioned above may perfectly be equipped with a loop antenna.
In a preferred mode of realization of the device according to the present invention the transmitter and/or receiver module comprises at least one of a display, of a keypad and of a microphone arranged along one side of the one part of the device, whereas the other part, which comprises the loop antenna, forms a preferably slideable or pivotable cover for the side.
Thereby, in a further preferred embodiment the loop antenna is fully integrated within the other part and along its periphery.
In a further preferred embodiment the other part, i.e. that part, wherein the loop antenna resides, is substantially flat. Thereby, in a further preferred embodiment the transmitter and/or receiver unit comprises at least one of a keypad, a display, a microphone along one side of the one part, whereby the other part provides for a cover of the one side and has one of a transparent and of an open central area, which is aligned with the keypad and/or the display and/or the microphone in one position of the other part with respect to the one part. Thereby, the loop antenna is arranged along the periphery of the other part. In a most preferred embodiment the device according to the invention is a wireless microphone or a wireless communication unit to at least one hearing device.